1. Field of the Invention
The present invention relates to an information recording apparatus, such as a DVD recorder, an information recording method, and a computer program product which makes a computer function as the information recording apparatus.
2. Description of the Related Art
In an information recording/reproducing apparatus for recording information onto an information recording medium, for example, an optical disc or the like, such as a CD-RW (Compact Disc-Read Only Memory) and a DVD-RW, the optimum power of a recording power is set by Optimum Power Control (OPC) processing in accordance with the type of the optical disc, the type and the recording speed of the information recording/reproducing apparatus, and the like. Namely, the calibration of the recording power is performed. This makes it possible to realize an appropriate record operation in the optical disc. For example, if the optical disc is inserted or loaded, and a command of writing is inputted, light intensity is changed step-by-step sequentially, and the data for trial writing is recorded into an OPC area, so that so-called trial writing is performed. Afterward, the data for trial writing recorded in this manner is reproduced. The reproduction result is judged by a predetermined evaluation reference, and the optimum power is set. optimum power is set.
Then, by irradiating laser light with the optimum power obtained by this OPC processing, the record operation is performed. Moreover, in recording (i.e. overwriting) new data into a recording area in which data is already recorded, the laser light is directly irradiated with the optimum power, without an independent delete operation. This is generally referred to as “Direct Overwrite”.
Japanese Patent Application Laying Open No. 2001-351249 discloses such a technique that whether the Direct Overwrite is performed with the optimum recording power or with a smaller recording power than the optimum recording power is selected in accordance with a condition of the recording area in which the data is recorded. This technique makes it possible to increase durability of the information recording medium which is an object of the record operation.
However, in the above-described Direct Overwrite operation, there is such a technical problem that the recording quality of the newly recorded data varies depending on the record condition of the previously recorded data. Specifically, in some cases, the record condition of the previously recorded data may cause various bad influences, such as reduction of a jitter value, increase in a reproduction error rate, and impossibility to obtain a preferable asymmetry value. Such conditions are not desirable from the viewpoint of the more preferable record or reproduction of the data.
In order to avoid this situation, it is also conceivable to perform the delete condition once, and then perform the record operation in another time. However, it doubles the labor in the irradiation of the laser light, and it is not desirable from the viewpoint of realization of the quick record operation.